check if a file exists on the hard drive ; File.Exists( );

1. if (System.IO.File.Exists("myfile.txt"))
2. {
3. //do stuff
4. }

siaqodb , if it is empty , null

  
      Siaqodb siaqodb = DBManager.Instance.GetInstance ();

        if(siaqodb!=null){
            showSiaqoDB();
        }
        else{
            Debug.Log("siqqo is empty");
        }

activeInHierarchy , 看有沒有被打開

        

else if (appPageGobj.activeInHierarchy)
        {
            aboutBackIndex = 2;
            appPageGobj.SetActive (false);
            menuPageGobj.SetActive(false);
        }

Object.Instantiate

initiate position:

 // Instantiates 10 copies of prefab each 2 units apart from each other

using UnityEngine;
using System.Collections;

public class ExampleClass : MonoBehaviour {
    public Transform prefab;
    void Start() {
        for (int i = 0; i < 10; i++) {
            Instantiate(prefab, new Vector3(i * 2.0F, 0, 0), Quaternion.identity);
            i++;
        }
    }
}

Instantiate is most commonly used to instantiate projectiles, AI Enemies, particle explosions or wrecked object replacements.

using UnityEngine;
using System.Collections;

public class ExampleClass : MonoBehaviour {
    public Rigidbody projectile;
    void Update() {
        if (Input.GetButtonDown("Fire1")) {
            Rigidbody clone;
            clone = Instantiate(projectile, transform.position, transform.rotation) as Rigidbody;
            clone.velocity = transform.TransformDirection(Vector3.forward * 10);
        }
    }
}

            GameObject item;
            I18nData holder = (I18nData)Resources.Load("I18nDataHolder", typeof(I18nData));
            if (holder.lang == "CN") {
                item = Instantiate(Resources.Load("Prefab/LitemButton1CN"))as GameObject;
            }
            else if (holder.lang == "EN") {
                item = Instantiate(Resources.Load("Prefab/LitemButton1EN"))as GameObject;
            }
            else if (holder.lang == "JP") {
                item = Instantiate(Resources.Load("Prefab/LitemButton1JP"))as GameObject;
            }
            else{
                item = Instantiate(Resources.Load("Prefab/ItemBubble"))as GameObject;
            }